1. Field of the Invention
The present invention relates to a sliding block for a torsional vibration damper, with a first surface section which, in the installation state, faces an adjacent spring element. The present invention relates, furthermore, to a separator sheet comprising such a sliding block, to a torsional vibration damper comprising such a sliding block or separator sheet and to a method for producing such a sliding block.
2. Description of the Related Art
A multiplicity of torsional vibration dampers or rotary vibration dampers in various fields of use are known from the prior art. The known torsional vibration dampers are used, in particular, in motor vehicle construction for the elastic coupling of the internal combustion engine and drive train. This is to prevent torsional vibrations from being transferred from the internal combustion engine to the drive train or the transmission. Such a transfer occurs particularly in internal combustion engines having comparatively few cylinders and with low rotational speeds. With effective damping of such vibrations, the internal combustion engine can be operated at lower rotational speeds, thus generally resulting in a reduced fuel consumption.
Thus, EP 1584838 A1 describes a torsional vibration damper with a drive-side primary element and an output-side secondary element, the primary element being coupled spring-elastically to the secondary element via a spring device, so that these elements can be rotated with respect to one another about a neutral position. The primary and secondary elements comprise in each case dogs which are adjacent to the spring device and which are designated below as a primary or a secondary dog. A torque prevailing at the primary element on the drive side can therefore be transferred by means of the primary dog first to the spring device and from the spring device to the secondary element via the secondary dog.
The spring device of the known torsional vibration damper consists of a plurality of spring elements arranged one behind the other in the circumferential direction of the torsional vibration damper, the spring elements being helical springs. Between the spring elements, what are known as sliding blocks are arranged, on which the successive spring elements are supported and which connect the spring elements to one another. The sliding blocks are provided, on their side facing radially away from the axis of rotation of the torsional vibration damper, with a sliding surface which senates for supporting the spring device with respect to a wall of the torsional vibration damper.
Since such friction between the sliding block and the wall causes increased wear on the sliding block, while the abrasion which occurs leads to a contamination of the lubricant, such as, for example oil, within the torsional vibration damper, EP 1584838 A1 proposes, furthermore, to at least partially use what are known as separator sheets. These separator sheets are designed as ring elements and sliding blocks fastened to them, the sliding blocks, in turn, being arranged between the spring elements. Since the sliding blocks are arranged on the ring element in such a way that the centrifugal forces occurring during the operation of the torsional vibration damper and acting on the sliding blocks are in sum compensated completely or partially, the term “separating element” is also used instead of the designation of sliding block.
Another solution for improving the slideability of the sliding block and for reducing the abrasion on the sliding surface of the sliding block is known from EP 0529669 A1. The two-mass flywheel disclosed in this document comprises two flywheels which are rotatable in relation to one another and are coupled rotationally elastically to one another by means of a rotary vibration damper device, the rotary vibration damper device comprising one of the spring devices described in the introduction, which is composed essentially of spring elements and sliding blocks. The sliding blocks of the known spring device may consist, for example, of metal and be hardened in the region of the sliding surface pointing radially outward. Moreover, in a further embodiment, a sliding block consisting of plastic is proposed, the sliding surface of which is coated with a slide-friendly coat or contains an admixture of slide-friendly material, in particular Teflon.
The above-described prior art led to a reduction in the wear on the sliding block of the known spring devices. The wear on the sliding blocks is nevertheless still too high, and, in particular, this may lead to a contamination of the lubricant within the torsional vibration damper.
An object of the present invention, therefore, is to provide a sliding block for a torsional vibration damper, which sliding block is particularly wear-resistant and generates only insignificant abrasion during operation. The object on which the present invention is based is, furthermore, to specify a separator sheet comprising such an advantageous sliding block. Moreover, the object on which the invention is based is to provide a torsional vibration damper, of which the abrasion-induced contamination during operation is particularly low. A further object on which the invention is based is to specify a method for producing such an advantageous sliding block.